PITTSBURGH (KDKA) – The University of Pittsburgh researcher who is accused of his wife’s cyanide poisoning death has waived extradition.

He was seen before a judge in West Virginia Monday, where he was arrested.

Dr. Robert Ferrante told the judge in court that he would willingly travel back to Pennsylvania.

State police in West Virginia were able to track down and arrest Ferrante with the use of license plate reading technology. Troopers set up patrols near a toll plaza and when Ferrante passed through, they stopped traffic.

“Because he fled the state of Pennsylvania, he was picked up here and we — he has to waive his right to extradition and be returned, which he did today,” said prosecutor Andy Dimick.

Troopers pulled Ferrante over for a traffic stop and he was then taken into custody without incident, police said.

The system automatically captures license plate numbers and compares them to a database through a processor in the trunk, making it easy to track down suspects.

Ferrente was taken into custody around 7 p.m. Thursday along Interstate 77 in Beckley, W. Va.

His wife, 41-year-old UPMC neurologist Autumn Klein, died April 20 after suddenly falling ill, and prosecutors say blood tests revealed a lethal level of cyanide. They allege that Ferrante had purchased more than a half-pound of cyanide two days before his wife’s illness.